Now let's get down to the important issue - how to make Welsh Rarebit. (whilst ignoring the fact that it was called Welsh Rabbit for a couple of centuries before it went posh). When we were children, grated Cheddar mixed with brown sauce toasted on bread was what we called Welsh Rabbit. Now every TV chef has their own gourmet version, usually involving creme fraich or some other authentic Welsh ingredient. Then the French got their hands on it - Croque Monsieur. Even our Delia mixes Parmesan with the English cheese, when we all know that Parmesan grown on a bush under the spaghetti trees in Italy.

I am not putting this recipe forward as the perfect Welsh Rabbit but I like it.
If it is too complicated for you get out the grater and the HP.

Method
1. Mix the mustard powder with a little stout in the bottom of a
small pan to make a paste, then stir in the rest of the stout and add
the butter and about 1 tsp Worcestershire sauce – you can always add
more later if you like. Heat gently until the butter has melted.
2. Tip in the cheese and stir to melt, but do not let the mixture
boil. Once smooth, taste for seasoning, then take off the heat and allow
to cool until just slightly warm, being careful it doesn't solidify.
3. Pre-heat the grill to medium-high, and toast the bread on both
sides. Beat the yolks into the warm cheese until smooth, and then spoon
on to the toast and cook until bubbling and golden. Serve immediately, with the rest of the stout in a glass.